#include "project.h"

#define BUFFER_SIZE 512

ring_t usart_rx_ring;
static uint8_t usart_rx_ring_buf[BUFFER_SIZE];

ring_t usart_tx_ring;
static uint8_t usart_tx_ring_buf[BUFFER_SIZE];

void
usart1_isr (void)
{
  uint8_t data;

  /* Check if we were called because of RXNE. */
  if (((USART_CR1 (USART1) & USART_CR1_RXNEIE) != 0) &&
      ((USART_SR (USART1) & USART_SR_RXNE) != 0)) {
    /* Retrieve the data from the peripheral. */
    data = usart_recv (USART1);
    ring_write_byte (&usart_rx_ring, data);
  }

  /* Check if we were called because of TXE. */
  if (((USART_CR1 (USART1) & USART_CR1_TXEIE) != 0) &&
      ((USART_SR (USART1) & USART_SR_TXE) != 0)) {
    if (ring_read_byte (&usart_tx_ring, &data)) {
      /*No more data, Disable the TXE interrupt, it's no longer needed. */
      USART_CR1 (USART1) &= ~USART_CR1_TXEIE;
    } else
      usart_send (USART1, data);
  }
}

void usart_kick (void)
{
  if (!ring_empty (&usart_tx_ring))
    USART_CR1 (USART1) |= USART_CR1_TXEIE;
}


int
_write (int file, char *ptr, int len)
{
  int ret;

  if (file == 1) {
    ret = ring_write (&usart_tx_ring, (uint8_t *) ptr, len);
    usart_kick();
    ring_write (&cdcacm_tx_ring, (uint8_t *) ptr, len);

    if (ret < 0)
      ret = -ret;

    return ret;
  }

  errno = EIO;
  return -1;
}




void
usart_init (void)
{
  ring_init (&usart_rx_ring, usart_rx_ring_buf, sizeof (usart_rx_ring_buf));
  ring_init (&usart_tx_ring, usart_tx_ring_buf, sizeof (usart_tx_ring_buf));
  /* Enable the USART1 interrupt. */
  nvic_enable_irq (NVIC_USART1_IRQ);
  /* Map pins */
  gpio_set_mode (GPIOA, GPIO_MODE_OUTPUT_50_MHZ,
                 GPIO_CNF_OUTPUT_ALTFN_PUSHPULL, GPIO_USART1_TX);
  gpio_set_mode (GPIOA, GPIO_MODE_INPUT, GPIO_CNF_INPUT_FLOAT,
                 GPIO_USART1_RX);
  /* Setup UART1 parameters. */
  usart_set_baudrate (USART1, 115200);
  usart_set_databits (USART1, 8);
  usart_set_stopbits (USART1, USART_STOPBITS_1);
  usart_set_parity (USART1, USART_PARITY_NONE);
  usart_set_flow_control (USART1, USART_FLOWCONTROL_NONE);
  usart_set_mode (USART1, USART_MODE_TX_RX);
  /* Enable USART1 Receive interrupt. */
  USART_CR1 (USART1) |= USART_CR1_RXNEIE;
  /* Finally enable USART1. */
  usart_enable (USART1);
}